Shoe shank



P- 1944- M. F. SULLIVAN 2,358,886

' SHOE .SHANK Filed Dec. 5, 1942 FIG].

INVENTOR M. F. SULLIVAN ATT RNEY Patented Sept. 26, 1944 V UNITED STA'I'ES PATENT GFFICE p I SHOE SHANK t MichaelF. Sullivan, St. Louis, Mo. Application December 3, 1942, Serial No. 467,675 Q 6 Claims; (01. 36-76) My invention relates to shoes and more particularly to an improved shank therefor;

One of the objects of my invention is toproduce an improved shoe shank which will give the shoe beneath the instep of a foot the desired permanent form and flexibility without the use of a resilient steel strip.

Another object is to produce an improved shank for a shoe in which the desired permanent form, is obtained by the use of a suitable cement material and a flexible reinforcing material. Other objects of my invention will become apparent from the following'description taken in connection with the accompanying drawing in which Figure 1 is a side view of a shoe whichis provided with my improved shank, parts; being shown in longitudinal section; Figure 2 is'a bottom view of a shoe showing. the completed shank construction prior to application of the outsole and heel; Figure 3 is a' sectional view taken on the line 3-3 of Figure 2; and Figure 4 is a'sectional view similar to Figure 3 but showing a modified construction. I p 1 Referring in detail to Figures 1 to 3,;there'is' shown 'a shoe comprising an upper I, an" insole 2, an outsole}, and a heel 4. As best shown in Figures 2 and 3, the upper is attached to the in-.

sole in the usual manner by having its lower marginal portion pulled over said insole and secured thereto by suitable means such as tacks or cement. To this assembly is secured the heel and the outsole in a well-known manner. In order 7 that the foot may be properly supported by the shoe insole and outsole, the shank portion thereof is usually provided with a reinforcing member or shank piece which has been in the form of a flat piece of thin steel. Such gives the shank of the shoe a permanent form, enabling the sole and insole to properly support the arch of the foot during the life of the shoe. This steel strip is resilient enough to also permit the proper flexibility of the sole. It is positioned between the insole and the outsole and secured to the insole by rivets, tacks, or the like. Such metal shank pieces are objectionable in some instances because they obstruct tacking, cause heel breakage, work through the outsole,- or shift, thus causing unbalanced walking. Steel under certain conditions, such as war, is also hard to obtain.

In accordance with my invention I have provided the shoe with an improved shank construction which will give the sole the proper permanent form and flexibility but does not require the use of a strip of steel as in prior shank constructions. In carrying out my invention I secure to '3) in the insole.

the outer surface of the insole at the shank, a piece of flexible'material 6 of a width to fit between the marginal edges I of the pulled over portion 8 of the upper and of a length to extend from the ball portion 9 of the insoleto the heel seat in. The material--ef strip 6 is preferably of any fibrous material, either animal, vegetable, or mineral origin, such as, for example, woven cloth, felt, paper, leather, or the like. To obtain the bestresults, it should be such that it can become impregnated with a substance in liquid form although any-material to which cement will adhere willsuffice. Also; in place of this strip, strands of small wire or a wire gauze can be employed. In the preferred construction'shown the strip is a fibre employed in making box toes.

-- The strip 6 of flexible material. or the like is secured to the bottom surface of the insole by a substance which has the characteristic of hard-,

ening by drying after being applied in liquid form orhardening by the application of heat. Such a suitable'substance is a cellulose nitrate cement I I such as pyroxylin or soluble gun cotton. To this is added a suitable plasticizer to make the cement somewhat flexible, examples thereof being dibutyl phylate and castor oil. This cement, when in. its liquid form, will readily penetrate the flexible material if suchis felt or cloth and upon hardening, the strip and cement will have the desired rigidity to give permanent form to the shank portion of the shoe yet also be somewhat flexible. The flexible strip reinforces the cement and prevents it from cracking or breaking when there is flexing of the insole and outsole. To give a foundation and greater strength to the cement and the structure as a whole, the cement has embodied therein any suitable filler substance 12 (indicated by the small particles) such as sawdust, rock wool, pulp, cotton, kapok, and so forth. Other substances which can be employed in place of the cellulose cement are synthetic resins, such as vinyl acetate and phenyl aldehyde.

In order to aid in making a proper joining of the strip and the insole, the strip 6 is provided with a series of longitudinally spaced holes ['3 which coincide with shallow recesses 14 (Figure These holes and recesses are filled with the cement embodying the filler during the securement of the strip to the insole. The cement'in these holes and recesses, when hardened thin, act as pegs to thus prevent any tendency of the strip to move relatively to the insole when there is flexing of the shank of the shoe.

A preferred method of assembly comprises first dipping the perforated strip in a suitable solvent or activator such as acetone. This prepared strip is then placed on the insole surface so that the holes coincide with the recesses. If desired, a thin layer of cellulose nitrate cement without the filler can be placed on the insole to adhere the strip in proper position. Next the strip is covered with the cement embodying the filler with the cement filling the holes and recesses and also extending over the edges of the strip onto the insole surface. The cement is allowed to dry which will occur in a short time. The shoe is now ready for the outsole which is put on in the usual manner.

It is to be noted that where nails or tacks are employed in laying the outsole there will be no obstruction encountered by the shank construction as would be the case where a steel strip shank piece is employed.

A slightmodification is shown in Figure 4. In this construction the insole 2 is provided with a. shallow longitudinal groove l5 of a size lightly larger than the strip in order to readily receive the strip when it is cemented to the insole. This construction is found useful when strip 6, which is to be used is quite thick or where it is desired to employ a plurality of thin strips one on top of the other. A suitable depth for the groove would be about one-sixteenth of'an inch. 7 Being aware of the possibility of modifications in the particular structure herein described without departing from the fundamental principles of my invention, I do not intend that its scope be limited except as set forth by the appended claims.

Having. fully described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In shoe shank construction the combination with an insole provided with longitudinally spaced recesses, of a strip of flexible material longitudinally adhered to the insole, said strip being provided with longitudinally spaced holes therein coinciding with the recesses, and a cemental substance capable of assuming a hardened form coverin thestrip and the adjacent part of the insole and filling the holes in said strip and the recesses in the insole.

2. In shoe shank construction the combination with an insole, of a strip of flexible material longitudinally adhered to the insole, said strip being of such length as to extend rearwardly from the ball portion of the insole to adjacent the heel portion, said strip and insole being provided with longitudinally spaced coinciding recesses filled .with the cellulose nitrate substance and filler.

4. In shoe shank construction, an insole provided with a longitudinally extending groOVe in its outer surface, a strip of flexible material mounted in said groove, and means comprisin a cellulose nitrate substance adhering the strip to the insole, covering said strip andextending to cover the insole surface adjacent-the edge of the strip.

5. In shoe shank construction the combination with an insole, of a flexible member applied to the insole and extendin longitudinally thereof at th shank of the shoe, said insole being so constructed as to provide an integral shoulder adjacent the longitudinal marginal edge of the member, and a cemental substance covering said flexible member and filling the space between the edge of the member and the shoulder, said substance being applied in liquid-form and having th characteristic of hardening after application to give rigidity to the flexible member and a permanent formto the insole.

6. In shoe shank construction the combination vwith an insole, of a flexible member applied to the insole and extending longitudinally thereof at the shank of the shoe, said insole being so constructed as to provide a recess adjacent the member, and a cemental substance covering said flexible member and filling the recess, said substance being applied in liquid form and having the characteristic of hardening after application to give rigidity to the flexible member and a permanent form to the insole.

MICHAEL F. SULLIVIAN. 

